The organizer William Medina explained that early entry is very important to him, because logistics could get pretty crazy if he dependend on word alone. He mentioned his had brevets were 10 people show up, or up to 200...not having enough supplys or support could be fatal to the organizers. He also told me they dont profit from this event because of permits and insurances. I registered using the website, but William said they could accept cash upon arrival with a 5 upcharge.

Im reading on RUSA.org, its very informative yet all the abreviations are a bit confusing at first
RUSA
RBA
ACP
Permanent...etc

from RUSA:
Can a person do a brevet series without joining RUSA?
Absolutely. The ACP's rules specifically state that participation in a brevet is not contingent on any affiliation. We at RUSA are dedicated to encouraging randonneuring by anyone, no matter what their affiliation or nationality. For example, imagine a British rider with a busy work-related travel schedule trying to earn his SR medal. He could do a brevet in England, one in France, another in America, and his final one in Canada. The results from all the various events go to the ACP in France, which issues brevets numbers validating a BRM ride. Once each ride is validated by the ACP, the approved card(s) with the validating brevet sticker is returned to the rider. One's national affiliation is not a consideration in these matters, nor where they did their brevets. What matters most is that they be ACP-approved BRM brevets and that the rider successfully finished each event inside the appropriate time limit, as noted on their brevet card.